Mud saver valve and method of operation of same

ABSTRACT

A mud saver valve (MSVIII), positionable at the bottom of the drill string, above the bit, which includes an elongated body portion; portion of the valve housing a compressible spring a pressure; a valve mechanism of a plunger and seat, the plunger moveable between open and closed positions within the valve by concentric actuator pistons; while in the closed position, drilling fluid cannot pass through the valve; when a combination of static and pump pressure exceeds the setting pressure of the spring, the plunger will be unseated by the concentric actuator pistons to the open position, at which time drilling fluid is allowed to through the valve; wherein when the valve is normally closed, as long as the fluid column pressure is less than the setting pressure, the valve remains closed, and allows the drill string to be disconnected and a section of pipe can be added without the fluid draining from the drill column above the bit, and thus saving fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation in part of co-pending U.S. patent application Ser. No. 13/077,053, filed Mar. 31, 2011 (issuing as U.S. Pat. No. 8,678,110 on Mar. 25, 2014), which claims the benefit of U.S. Provisional Application Ser. No. 61/320,037, filed Apr. 1, 2010, each of which is hereby incorporated herein by reference and priority to each of which is hereby claimed.

International Application Serial No. PCT/US2011/030690, filed Mar. 31, 2011 (published as No. WO 2011/123617 on Oct. 6, 2011), is hereby incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

REFERENCE TO A “MICROFICHE APPENDIX”

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to oilfield valves. More particularly, the present invention relates to a mud saver valve when installed to prevent the loss of drill fluid during starting operation in deep water wells using a combination of static fluid pressure and flow pressure to open the valve and mechanical spring forces to close the valve. In a second embodiment the valve utilizes a plunger and seat mechanism to replace the sliding sleeve and non-concentric actuator pistons replaced with larger concentric actuator pistons.

2. General Background of the Invention

When drill pipe and other tubular strings are lowered into or raised out of a well bore, including, but not limited to, during the drilling of the wellbore, it is quite common, particularly in the oil and gas field, for the drill pipe and other tubular strings to be filled with mud of the type used in drilling techniques. The mud would typically be pumped into the upper end of the drill string after it has been connected to the drill string below it and/or as it is being lowered into a wellbore. As the next joint is added to the drill string, the connection is typically disconnected from the drill string to allow the next section of drill pipe to be connected to the string. When the fluid connection is disconnected, there should preferably be a mud saver valve in place to retain this fluid and prevent it from flowing out onto the work area and environment. The advantages of using such a valve are well known and include saved mud cost, decreased chances of pollution, and increased safety to rig personnel. To avoid this loss of mud during these types of operations there is needed a mud saver valve which could be positionable just above the drilling bit or just below the bend sub to prevent the loss of drill fluid during starting operation in deep water wells, which reduces the amount of drilling fluid required to start a well and reduces the pollution of the mud bottom with drilling fluid and weighting material.

This invention improves the Mud Saver Valve II, as disclosed in U.S. patent application Ser. No. 13/077,053, issuing as U.S. Pat. No. 8,678,110 on Mar. 25, 2014. The Mud Saver Valve II replaced the nitrogen dome with a mechanical compression spring that is compressed during the valve assembly process to a certain pre load found in the original Mud Saver Valve discussed above. The mechanical spring pre load provides the closing force acting on the valve's Mud Saver Valve II and also opens the closing side of the multiple pistons to the annulus pressure at the valve location depth in the well bore.

The Mud Saver Valve II replaced the original Mud Saver Valve which utilized a nitrogen dome with a mechanical compression spring that was compressed during the valve assembly process to a certain pre load found in the original Mud Saver Valve discussed above. This mechanical spring pre load provides the closing force acting on the valve's Mud Saver Valve II also opens the closing side of the multiple pistons to the annulus pressure at the valve location depth in the well bore.

To force the original Mud Saver Valve to open its fluid pathway through the valve, pressure inside the drill pipe at the valve's location in the well bore has to rise above the pre charge pressure of the nitrogen dome plus whatever pressure is required to overcome the friction force of the piston seals. To accomplish this either direct hydrostatic head pressure or the combination of direct hydrostatic head pressure and flow pressure generated by the mud pumps are required.

With the original Mud Saver Valve the amount of pump pressure required to open the valve is a function of the depth of the tool in the well bore. The deeper the tool, the higher the hydrostatic head pressure and the lower the pump pressure required to open the valve.

With the original Mud Saver Valve the valve could be set to open at any particular depth by adjusting the nitrogen pre charge pressure prior to entering the well bore.

In the Mud Saver Valve II which is disclosed in a patent soon to issue, the valve replaced the nitrogen dome with a mechanical compression spring that is compressed during the valve assembly process to a certain pre load found in the original Mud Saver Valve discussed above. This mechanical spring pre load provides the closing force acting on the valve's Mud Saver Valve II also opens the closing side of the multiple pistons to the annulus pressure at the valve location depth in the well bore. Further, as with the original Mud Saver Valve, the opening side of the multiple pistons are fed with the pressure in the drill pipe at the valve's location depth in the well bore. Further, in a static condition without flow if the fluid mud in the annulus and the fluid mud in the drill pipe are the same weight per unit volume, then (neglecting friction in the piston seals) the differential pressure working across the multiple actuator pistons is zero. The pump pressure required to open the Mud Saver Valve II is no longer a function of the depth of the valve in the well bore. The pump pressure required to open the Mud Saver Valve II, at any well bore depth, is only a function of the mechanical compression spring pre load and whatever pressure is required to overcome the friction of the piston seals. In the Mud Saver Valve II design the amount of friction of the piston seals can be dramatically reduced by converting to mechanical labyrinth type seal. Labyrinth seals have no physical contact between the sealing surfaces. As a consequence of this the friction of the seal is eliminated. However, a small amount of leakage will pass through the seal. The amount of fluid following through the valve can be 12 barrels per min. (504 gal/min (1908 liters/min)) The small amount of leakage past the two (2) 0.625 inch (1.59 cm) diameter pistons is thought to be negligible.

The following US patents are incorporated herein by reference:

TABLE PATENT No./ ISSUE DATE Publication No. TITLE DD-MM-YYYY 20030102131 Mudsaver Valve with 06-05-2003 retrievable inner sleeve. 20050189144 Mud Saver Valve 09-02-2005 20050236191 Drill String Valve Assembly 10-27-2005 20010037900 Mud Saver Kelly Valve 11-08-2001 20070039759 Mud Saver Valve 02-22-2007 7,048,079 Mud Saver Valve 05-23-2006 6,053,191 Mud-Saver Valve 04-25-2000 6,640,824 Mud Saver Kelly Valve 11-04-2003 6,662,886 Mudsaver Valve with 12-16-2003 Dual Snap Action

BRIEF SUMMARY OF THE INVENTION

The mud saver valve of the present invention which is referred to herein as Mud Saver Valve III, or MSVIII, is an improvement over the Mud Saver Valves I and II, and solves the problems in the art in a simple and straightforward manner. What is provided is an improved Mud Saver Valve III (MSVIII) including a seat and plunger in the operation, replacing the sliding sleeve found in the MSVII. The improved Mud Saver Valve III improves the operation from the Mud Saver Valve II, as disclosed and claimed in U.S. patent application Ser. No. 13/077,053 in improving (1) the valve actuation and stability; (2) the valve flow efficiency; and (3) pressure and plunger closing forces. The Valve Actuation of the Mud Saver Valve 101 MSVIII is improved in the design of the MSVIII. The slotted cage and sliding sleeve mechanism in the Mud Saver Valve II (MSVII) is replaced in the MSVIII with a heavy-duty plunger and seat mechanism as seen in isolated view in FIG. 30. The plunger and seat will stop the valve mechanism from sticking in its fully closed and fully opened positions. The design of the MSVIII involves the removal of the (2) two small non-concentric actuator pistons, spaced 180° apart on the MSVII design, which are now replaced in the MSVIII design with (2) two much larger and concentric actuator pistons. The replacement of the two small non-concentric actuator pistons with two large concentric actuator pistons, spaced inline and a significant distance apart on the plunger mandrel, improves the valve's ability to open and close without sticking anywhere in the mid stroke of the valve actuator. The ratio of the distance between the two inline and concentric actuator pistons to the diameter of the largest actuator piston 107 is in the order of 6:1.

Therefore, it is a principal object of the present invention to provide an improved Mud Saver Valve III which improves the operation from the Mud Saver Valve II, as disclosed and claimed in U.S. patent application Ser. No. 13/077,053 in improving (1) the valve actuation and stability; (2) the valve flow efficiency; and (3) pressure and plunger closing forces.

An embodiment of the present invention comprises a mud saver valve, positionable at a bottom of a drill string, above a bit, and further comprises an elongated body portion; a pressure portion housing a compressible spring; and a valve mechanism positioned within the valve. While in a closed position, drilling fluid cannot pass through the valve and when a combination of static and pump pressure exceeds the setting pressure of the spring, the valving mechanism will be moved by concentric actuation pistons to the open position, at which time drilling fluid is allowed to flow through the valve.

In another embodiment of the present invention, the valve mechanism comprises a plunger seated against a plunger seat moveable between open and closed positions within the valve by the concentric actuator pistons.

In another embodiment of the present invention, the plunger is moved to the open position by means of two concentric actuator pistons.

In another embodiment of the present invention, as long as the spring pressure is greater than the setting pressure, the valve remains in the closed position to allow the drill string to be disconnected, so that a section of pipe can added without the fluid draining from the drill column above the bit, resulting in a saving of fluid.

In another embodiment of the present invention, the plunger is moved to the open position by means of two concentric actuator pistons and wherein by opening a closing side of the concentric actuation pistons to annulus pressure at any mud saver valve location, the valve's cracking pressure becomes independent of the depth of the tool in the hole.

Another embodiment of the present invention comprises a mud saver valve, positionable at a bottom of a drill string, above a bit, which further comprises an elongated body portion; a pressure portion housing a compressible member, such as a coiled spring; and a valve mechanism which comprises a plunger seated in a plunger seat in the closed position and moveable between open and closed positions within the valve. While in the closed position, drilling fluid cannot pass through the valve and when a combination of static and pump pressure exceeds the setting pressure of the compressible member, the plunger will be moved by the concentric actuator pistons to the open position, and drilling fluid is allowed to flow through the valve.

Another embodiment of the present invention comprises a mud saver valve, positionable at a bottom of a drill string, above a bit, and further comprises an elongated body portion; a pressure portion housing a compressible spring; and a valve mechanism, further comprising a plunger moveable by a pair of concentric actuator pistons between open and closed positions within the valve. While the plunger is seated in the plunger seat in the closed position, drilling fluid cannot pass through the valve. When a combination of static and pump pressure exceeds the setting pressure of the spring, the plunger will be moved by the pair of concentric actuation pistons to the open position, so that drilling fluid is allowed to flow through the valve.

In another embodiment of the present invention, the plunger is unseated from the plunger seat and moved to the open position by means of a pair of concentric actuator pistons.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:

FIG. 1 is a trimetric view of the preferred embodiment of the apparatus of the present invention;

FIG. 2 is a front view of the preferred embodiment of the apparatus of the present invention;

FIG. 3 is a front section view of the preferred embodiment of the apparatus of the present invention;

FIG. 4 is a front section view of the preferred embodiment of the apparatus of the present invention;

FIG. 5 is a front section view of the preferred embodiment of the apparatus of the present invention;

FIG. 6 is a front section view of the preferred embodiment of the apparatus of the present invention;

FIG. 7 is a front section view—Valve Actuator Piston—Seal Assembly

FIG. 8 is a top view of the preferred embodiment of the apparatus of the present invention;

FIG. 9 is a front view of the preferred embodiment of the apparatus of the present invention;

FIG. 10 is an isometric view of the preferred embodiment of the apparatus of the present invention;

FIG. 11 is a front section view of the preferred embodiment of the apparatus of the present invention;

FIG. 12 is a front section view of the preferred embodiment of the apparatus of the present invention;

FIG. 13 is a front section view of the preferred embodiment of the apparatus of the present invention in the closed position;

FIG. 14 is a front section view of the preferred embodiment of the apparatus of the present invention in the open position;

FIG. 15A illustrates an isometric view of an alternate embodiment of the Mud Saver Valve II of the present invention;

FIG. 15B illustrates a front view of an alternate embodiment of the Mud Saver Valve II of the present invention;

FIG. 16 illustrates an alternate embodiment of the mud saver valve II of the present invention with the drill bit and drill string or pipe shown in phantom view.

FIG. 17 illustrates a front section view in the close of the alternate embodiment of the Mud Saver Valve II in the closed position;

FIG. 18 illustrates a front section view of an alternate embodiment of the Mud Saver Valve II illustrating the major sub assemblies;

FIG. 19 illustrates a front section view of the alternate boxed end sub pre assembly of the Mud Saver Valve II of the present invention;

FIG. 20 illustrates a front section view of an alternate valve actuator pre assembly of the Mud Saver Valve II of the present invention;

FIG. 21 illustrates a front section view of the alternate pin end sub pre assembly of the Mud Saver Valve II of the present invention;

FIG. 22 illustrates a front section view (cut) of the Mud Saver Valve II of the present invention in the closed position;

FIG. 23 illustrates a front section view (cut) of the Mud Saver Valve II in the open position;

FIGS. 24 and 25 illustrate modified embodiments of the Mud Saver Valve II of the present invention from that shown in FIGS. 22 and 23;

FIG. 26A illustrates an end view of the Mud Saver Valve III of the present invention in the closed position, while FIG. 26B illustrate an overall side view of the improved Mud Saver Valve III along lines A-A in FIG. 26A;

FIG. 27 illustrates an isolated view of a portion of the Valve in FIG. 26B at area B;

FIG. 28 illustrates an isolated view of a portion of the Valve in FIG. 26B defined by area C in FIG. 26B;

FIG. 29A illustrates an end view of the Mud Saver Valve III of the present invention in the open position, while FIG. 29B illustrates an overall side view of the improved Mud Saver Valve III along lines A-A in FIG. 29A;

FIG. 30 illustrates an isolated view of a portion of the Valve in FIG. 29B at area B in FIG. 29B; and

FIG. 31A illustrates a drill bit and FIG. 31B illustrates a partial side view of the Mud Saver Valve III positioned above the drill bit on a typical drill string.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 through 25 illustrate the embodiments of the Mud Saver Valve I and II, while FIGS. 26A-31B illustrate the improved Mud Saver Valve III of the present invention.

Prior to a discussion of the drawing figures, it should be kept in mind that the overall function of the Mud Saver Valve II and Mud Saver Valve with Concentric Pistons is the same as the original Mud Saver.

When the rig's mud pumps that circulate mud down the drill pipe to the drill bit at the bottom of the well bore and then return the mud, contaminated with drilled shavings, up the annulus to the BOP stack and finally either take the returning mud up the (subsea riser/spool) or (choke/kill lines) are off, a mechanical device in the original Mud Saver Valve and modified mechanical devices in the Mud Saver Valve II and Mud Saver Valve with Concentric Pistons force these valves to their closed positions and do not allow mud to flow through them.

When the rig's mud circulating pumps are turned on pressures working on respective mechanical devices in each of these three (3) Mud Saver Valve designs force the valves to open and allow the mud to flow through the valves.

The overall function of these valves is to capture the large volume of conditioned clean mud that is in the drill pipe from just above the drill bit at the bottom of the well bore up to the rig floor. These Mud Saver Valves will not allow the clean mud in the drill pipe to drain out of the bottom of the pipe and into the contaminated mud in the annulus as individual pipe stands are tripped in and out of the well bore.

The original Mud Saver Valve uses a pre charged nitrogen dome chamber to feed pre charge pressure to the closing side of multiple pistons that are arranged in an equally spaced circular pattern around the center axis of the valve. The force created by the pre charge pressure acting on the multiple pistons force a slidable sleeve to close the fluid pathway through the valve.

To force the original Mud Saver Valve to open its fluid pathway through the valve, pressure inside the drill pipe at the valve's location in the well bore has to rise above the pre charge pressure of the nitrogen dome plus whatever pressure is required to overcome the friction force of the piston seals. To accomplish this either direct hydrostatic head pressure or the combination of direct hydrostatic head pressure and flow pressure generated by the mud pumps are required.

With the original Mud Saver Valve the amount of pump pressure required to open the valve is a function of the depth of the tool in the well bore. The deeper the tool, the higher the hydrostatic head pressure and the lower the pump pressure required to open the valve.

With the original Mud Saver Valve the valve could be set to open at any particular depth by adjusting the nitrogen pre charge pressure prior to entering the well bore.

The Mud Saver Valve II replaces the nitrogen dome with a mechanical compression spring that is compressed during the valve assembly process to a certain pre load. This mechanical spring pre load provides the closing force acting on the valve's Mud Saver Valve II also opens the closing side of the multiple pistons to the annulus pressure at the valve location depth in the well bore.

As with the original Mud Saver Valve, the opening side of the multiple pistons are fed with the pressure in the drill pipe at the valve's location depth in the well bore.

In a static condition without flow if the fluid mud in the annulus and the fluid mud in the drill pipe are the same weight per unit volume then (neglecting friction in the piston seals) the differential pressure working across the multiple actuator pistons is zero.

The pump pressure required to open the Mud Saver Valve II is no longer a function of the depth of the valve in the well bore. The pump pressure required to open the Mud Saver Valve II, at any well bore depth, is only a function of the mechanical compression spring pre load and whatever pressure is required to overcome the friction of the piston seals.

In the Mud Saver Valve II design the amount of friction of the piston seals can be dramatically reduced by converting to mechanical labyrinth type seal. Labyrinth seals have no physical contact between the sealing surfaces. As a consequence of this the friction of the seal is eliminated. However, a small amount of leakage will pass through the seal. The amount of fluid following through the valve can be 35 barrels per min. (1,500 gallons/min (5,678 liters/min)) The small amount of leakage past the two (2) 0.625 inch (1.59 cm) diameter pistons is thought to be negligible.

Turning now the drawing Figures, first FIG. 13 illustrates the Mud Saver Valve II in the closed position. Spring 24 is the closing compression spring that is preloaded at assembly and pushes against a spring closing sleeve 23 which ultimately pushes against valve actuator—sliding sleeve (open/close) 32 and closes the valve.

The annulus pressure is fed through annulus pressure feed port 3 to the closing side of valve actuator—piston 34 at valve actuator—piston close valve pressure side 42.

The pressure inside the drill string or pipe 17, which with the same weight fluid in the pipe 17 and annulus is equal to the annulus pressure, is fed down inlet fluid conductor 6 to the valve actuator radial port through valve actuator radial port 7 and into inlet fluid cavity between the valve actuator housing and the valve actuator sliding sleeve 8, where it is blocked by sliding sleeve 32 and fed to valve actuator—piston open valve pressure side 41. Since the annulus and pipe pressure are equal the differential pressure across the pistons 34 is zero and the springs 24 pre load holds the valve closed.

FIG. 14 illustrates the Mud Saver Valve II in the open position. Fluid is shown flowing through the valve. At the moment when the mud pumps are turned on and sliding sleeve 32 is in the closed position, as shown in FIG. 13, pressure builds quickly at valve actuator 41 which moves inlet fluid piston 34 to the open position. Fluid flows down inlet fluid conductor 6 and then through valve actuator radial port 7 where it enters inlet fluid cavity between the valve actuator housing and the valve actuator sliding sleeve 8 before flowing through cage radial inlet ports 55 and entering the orifice inlet 56. The flow across the orifice 52 creates a pressure differential across the orifice item 52. For all practical purposes the pressure differential across the orifice 52 is approximately equal to the pressure differential across the piston 34. The pressure at orifice inlet 56 is approximately equal to the pressure at actuator-actuator-piston open 41. The pressure at orifice outlet 57 is approximately equal to the pressure at valve actuator-piston close 42. Practically, the orifice can be considered to be anything from valve actuator-piston open 41 through the drill bit that creates any pressure drop (restrictions). High flow rates with high pressure drop will insure that the valve stays completely open. If the flow rate drops the valve will throttle itself working the pressure differential across the piston 34 against the spring preload 24.

Recent testing of the Mud Saver Valve II, as represented in FIGS. 1-14 performed as expected. At a very low flow rate (less than 1 gal/min (3.78 liters/min)) the Mud Saver Valve II cracked open at the correct pressure and then repeatedly closed and re-cracked open as expected. However, there are a couple of points which we would like to cover as an alternate embodiment of the Mud Saver Valve II and represented in FIGS. 15-23.

FIGS. 15A-18 illustrate an alternate embodiment 60 of the Mud Saver Valve II. A box end pre-sub assembly 70, and annulus pressure feed port 71 which is kidney shaped, are shown. FIG. 18 illustrates the major subassemblies, including the box and pre-sub assembly 70, valve components 80, 90, and valve actuator housing 40. FIG. 16, shows the alternate embodiment of the Mud Saver Valve II, positioned on the drill string or pipe 17, just above drill bit 83.

The first area of interest is the two (2) small pistons represented in FIGS. 1-14. There is no guarantee that both small pistons will function in the exact same way. If one piston should hang up, for what ever reason, it may cause the valve to cock and stick. Also, the cross sectional area of the two (2) pistons is very small and therefore requires a fairly high cracking pressure even though the closing spring pre load force is relatively low at 600 pounds (272 kg). The high crack pressure is wasted pressure that gets added to the pump pressure requirements as the valve is throttled between the fully closed and fully opened positions.

Piston 74, 84 of FIG. 17. In the alternate embodiment the two (2) small pistons that were positioned radially offset from the center axis of the valve are replaced with these two (2) much larger pistons that are positioned concentrically with the center axis of the valve and each other. The two (2) much larger pistons are also concentric with other important valve components such as reference 80, 90, shown more clearly in FIG. 18.

This design represented in FIG. 17 will allow for a much lower cracking pressure and much higher spring pre load closing force. Also if cast iron piston seal or Teflon split piston seals are used they will provide very low friction forces and high ware resistance. However these seals will allow a very small amount of fluid to leak past them.

The second area of interest is the Pin End (bottom) Sliding Sleeve Seal represented as sliding sleeve main seal 33 of FIG. 6. Reference is made to FIG. 13 and FIG. 14 showing the valve in the closed and open position. Notice that as the valve opens the Pin End (bottom) Sliding Sleeve Seal must pass over the radial ports in the cage represented as cage radial inlet ports 55 of FIG. 14. Also notice that the Box End (top) Sliding Sleeve Seal is Ok as it never passes over the radial ports.

The Pin End (bottom) Sliding Sleeve Seal may be cut or otherwise damaged as it passes over the radial ports. The relatively low closing force of the spring may not allow the valve to close if part of the damaged seal gets caught up in the Sliding Sleeve mechanism.

In the alternate embodiment the Pin End (bottom) Sliding Sleeve Seal is made larger in diameter and moved to an alternate embodiment of the Cage. Reference FIG. 21, reference 93, alternate Cage (Plunger Type), represents the larger Sliding Sleeve Seal, reference 91 of FIG. 21 and the snap ring and back up washer, reference 92 of FIG. 2, that is used to hold the seal in place.

The alternate embodiment of the Sliding Sleeve, alternate valve actuator-sliding sleeve (Open/close) 82 of FIG. 20 has a very gradual tapered nose which is designed to function as a plunger that slides in under the larger seal, Reference 91 of FIG. 21.

FIG. 22 shows the Mud Saver Valve with Concentric Pistons in the closed position. Spring 24 is the closing compression spring that is pre loaded at assembly and pushes against alternate Spring Closing Sleeve 77 which ultimately pushes against alternate valve actuator-sliding sleeve (Open/close) 82 and closes the valve.

The annulus pressure is fed through Alternate Annulus Pressure Feed Port-Kidney Shaped 71 at Valve Actuator-Piston Close Valve Pressure Side 42.

The pressure inside the pipe which with the same weight per unit volume of fluid in the pipe and annulus is equal to the annulus pressure is fed down Inlet Fluid Conductor 6 to the Valve Actuator Radial Port 7 and into Inlet Fluid Cavity 8 between the Valve Actuator Housing 40 and the Valve Actuator Sliding Sleeve 82 where it is blocked by alternate valve actuator-sliding sleeve (open/close) 82 and fed to Valve Actuator-Piston Open Valve Pressure Side 41.

Since the mud pumps are turned off and the fluid in the pipe has the same weight per unit volume as the fluid in the annulus then the pipe and annulus pressures are equal and the differential pressure across the pistons 84, 74 is zero and the pre load force of the spring 24 holds the valve closed.

FIG. 23 shows the Mud Saver Valve with Concentric Pistons in the open position. At the moment the mud pumps are turned on the fluid in the pipe is blocked from flowing by sliding sleeve 82 shown in the closed position in FIG. 22. Very quickly pressure builds at valve actuator 41. When the pressure at valve actuator 41 rises high enough above the annulus pressure at valve actuator 42 to over come the spring per load force provided by spring 24 the pistons 84, 74 will move together to open a fluid pathway through the valve.

Fluid flows down inlet fluid conductor 6 and then through the radial ports 7 where the fluid then enters inlet fluid cavity 8 before flowing through Cage Radial Ports 55 and entering The Orifice Inlet 56. The flow across Fixed Orifice 52 creates a pressure differential across Fixed Orifice 52. For all practical purposes the pressure differential across fixed orifice 52 is approximately equal to the pressure differential across pistons 84, 74. The pressure at Orifice Inlet 56 is approximately equal to the pressure at valve actuator-piston open 41 and the pressure at Orifice Outlet 57 is approximately equal to the pressure at valve actuator-piston close 42.

Practically the Orifice can be considered to be anything from valve actuator-piston open 41 through the drill bit 83 that creates any pressure drop (restriction). High flow rates with high pressure drops will insure that the valve stays completely open. If the flow rate drops the valve will throttle itself working the pressure differential across the pistons 84, 74 against the spring preload of spring 24.

FIGS. 24 and 25 illustrate an alternative embodiment of the valve 60 as that shown in FIGS. 22 and 23 as discussed above. To allow for greater flow capacity, in this embodiment, the cage radial inlet ports 55 are being removed and there are installed fluid guide noses to help the fluid flow entering and leaving inlet fluid cavity 8 between the valve actuator housing and the valve actuator sliding sleeve. The valve actuator-sliding sleeve main seal 33 is also removed. The seal 91 can represent metal to metal conical sealing surfaces, and a vertical face type seal could be employed.

If the fluid in the drill string or pipe 17 and the fluid in the annulus have the same weight per unit volume then the cracking pressure of the valve at any depth is equal to the cracking pressure of the valve at sea level. Therefore, there is no longer a concern about the valve opening because the hydrostatic pressure due the tool's depth and the weight of the fluid per unit volume in the pipe exceeded the spring cracking pressure.

Turning now to FIGS. 26A through 31B, which illustrate the Mud Saver Valve III (MSVIII) 101, where in general there is illustrated a seat and plunger in the operation, replacing the sliding sleeve found in the MSVII. The improved Mud Saver Valve III improves the operation from the Mud Saver Valve II, as disclosed and claimed in U.S. patent application Ser. No. 13/077,053 in improving (1) the valve actuation and stability; (2) the valve flow efficiency; and (3) pressure and plunger closing forces, as will be discussed below and in reference to FIGS. 26A through 31B.

1—Improved Valve Actuation and Stability.

The Valve Actuation of the Mud Saver Valve 101 MSVIII is improved in the design of the MSVIII. The slotted cage and sliding sleeve mechanism in the Mud Saver Valve II (MSVII) is replaced in the MSVIII with a heavy-duty plunger 104 and seat 113 mechanism as seen in isolated view in FIG. 30. The plunger 104 and seat 113 will stop the valve mechanism from sticking in its fully closed and fully opened positions.

The Stability of the MSVII is improved in the design of the MSVIII. The removal of the (2) two small non-concentric actuator pistons, spaced 180° apart on the MSVII design, are now replaced in the MSVIII design with (2) two much larger and concentric actuator pistons 107 and 108. The replacement of the (2) two small non-concentric actuator pistons with (2) two large concentric actuator pistons 107 and 108, as seen in FIGS. 27 and 28, spaced inline and a significant distance apart on the plunger mandrel 106, improves the valve's ability to open and close without sticking anywhere in the mid stroke of the valve actuator. The ratio of the distance between the (2) two inline and concentric actuator piston to the diameter of the largest actuator piston 107 is in the order of 6:1.

2—Improved Valve Flow Efficiency.

Fixed displacement hydraulic pump circuits obey the laws of conservation of matter and energy. Conservation of matter states that the amount of fluid that enters Inlet Fluid Port at Box 111, over a certain period of time, must equal the same amount of fluid that exits the Outlet Fluid Port at Pin 112 over that same period of time.

Conservation of energy, (Bernoulli's Equation) states that Total Energy (head) at the Inlet Fluid Port at Box 111 must equal the Total Energy (head) at the Outlet Fluid Port at Pin 112. However, because there are no perfect fluids, no perfect valve components and no perfect line pipe, there are always energy losses resulting from the frictional effects of the flowing fluid. These frictional effects show up as a pressure drop across the valve from its Inlet Fluid Port at Box 111 through its Outlet Fluid Port at Pin 112.

The Valve Flow Efficiency of the MSVII is improved in the design of the MSVIII. In reference to the Valve Open Position 115, it is critical to minimize the overall pressure drop from Inlet Fluid Port at Box 111 through Outlet Fluid Port at Pin 112. This is particularly true in the Valve Actuation Housing 102. The Higher Valve Flow Efficiency in the MSVIII corresponds to less energy loss and lower pressure drops across the Valve Actuator Housing 102. The Higher Valve Flow Efficiency results from the removal of (4) four 90° sharp turns that existed in the Valve Actuator Housing of the MSVII. Also, as stated before, the slotted hole cage design of the MSVII is removed in the design of the MSVIII. Finally, the flow path (cross sectional area) through the Valve Actuator Housing 102 is designed to be a constant. This reduces the nozzle and diffuser effects resulting from unnecessary changes in the velocity of the fluid as it flows through the Valve Actuator Housing 102. Another net effect of the lower and constant fluid velocity through the Valve Actuator Housing 102 is less erosion of the Valve Actuator Housing's 102 Internal Parts. The Plunger Nose (Bolt On) 105 helps direct the fluid leaving the Valve Actuation Housing 102.

3—Pressure and Plunger Closing Forces as the MSVIII Descends:

As the drill bit descends from the Rig Floor to the sea floor, the operator continually fills the drill pipe with weighted drilling mud of 11 to 16 pounds per gallon. The hydrostatic pressure in the MSVIII continually increases as it is filled and lowered to the sea floor.

As the drill bit descends from the Rig Floor to the sea floor, the open annulus pressure feed ports 110 are continuously surrounded and filled with 8.6 pounds per gallon seawater. The Bi-Directional Actuator Piston (Large) 107 uses seals 116 to hold annulus pressure. The Bi-Directional Actuator Piston (Large) 107 uses seals 117 to hold Internal Valve Pipe Pressure. The Bi-Directional Actuator Piston (Smaller) 108 uses seals 118 to hold Annulus Pressure. The Bi-Directional Actuator Piston (Smaller) 108 uses seals 119 to hold Internal Valve Pipe Pressure. At Valve assembly, screwing on of the Box End Sub 100 causes a mechanical compressive plunger load on the valve's plunger seat 113 of 3,088 pounds.

Hypothetically in 10,000 feet of seawater and drilling fluid at 14 pounds per gallon, the hydrostatic pressure working on the Bi-Directional Actuator Pistons 107 and 108 will decrease the plunger's compression Spring 109 load from 3,088 pounds to 500 pounds. However, further drilling with the bit into deeper formations will not cause a further reduction in the plunger's compressive Spring 109 load of 500 pounds. As long as the same specific weight drilling mud is flowing through the system, the operator need not be concerned that the increase in hydrostatic pressure due to drilling depth, will force the valve to open. It is not necessary to continually change to a stronger spring 109 with a higher spring rate as the well is drilled deeper. As shown in FIG. 29B, the Pin End Sub 103 attaches the MSVIII to the Box End of the lower drill collar. The Valve Body 101 attaches the Valve Actuator Housing to the Box End Sub 100. The MSVIII Closed Position 114 shows the Plunger Compression Spring 109, Bi-Directional Actuator Piston (Large) 107, Bi-Directional Actuator Piston (Small) 108, Plunger 104 seated in the Plunger Seat 113 (see FIGS. 26A-26B). The MSVIII Open Position 115 shows the Plunger 104, Mandrel 106, and Compression Spring 109 in the open position (see FIGS. 29A-29B).

Example of Valve Operation

In operation, the mud saver valve (MSVIII) 101 is positionable at the bottom of the drill string 150, above the drill bit 160 as seen in FIGS. 31A-31B. The MSVIII 101 includes an elongated body portion or housing 102, and a pressure portion housing a compressible plunger compression spring 109. There is further provided a valve mechanism, which comprises a plunger 104, moveable by a pair of concentric large and small actuator pistons 107 and 108 respectively, with the plunger 104 moving from a seated position on a plunger seat 113, to the unseated or open position within the valve 101. During operation, while the plunger 104 is seated in the plunger seat 113 in the closed position, drilling fluid cannot pass through the valve 101, and when a combination of static and pump pressure exceeds the setting pressure of the spring 109, the plunger 104 will be moved by the pair of concentric actuation pistons 107, 108, to the open position, at which drilling fluid is allowed to flow through the valve 101.

In a typical set up of the MSVIII valve 101 for a Pump & Dump Operation at a depth of 10,000 feet; the Seawater would be at 8.6 pounds per gallon and the drilling mud at 14 pounds per gallon. The MSVIII 101 is assembled with a compression spring 109 that creates 3,082 pounds of closing force between the Plunger 104 and Seat 113 as the Box End Sub 100 is screwed on tightly to the Valve Body 102. At this point the Valve 101 is on dry land and there are no fluid pressures in the MSVIII 101 working to either open or close either one or the other Bi-Directional and Concentric Actuator Pistons 107 and 108. In the transition from the Valve 101 being located on the Rig Floor to the Valve 101 being lowered to the seafloor, the Hydrostatic Pressure continually rises from 0 to 7,272 pounds per square inch in the Valve Pipe and 0 to 4,467 pounds per square inches in the Annulus Feed Ports 110. These (2) two Different Hydrostatic Pressures working on (2) two slightly different bores for the Bi-Directional & Concentric Actuator Piston 107, 108, reduces the closing pressure of Plunger 104 sealing closed on the plunger seat 113 from 3,082 pounds to 500 pounds.

As the bit drills deeper and deeper into the subsea formation, the 500 pound closing pressure on the Plunger 104 on plunger Seat 113 does not increase with the higher and higher Hydrostatic Pressure due to increasing depth. As long as the same Drilling fluid Weight flows through the system, there will not be an increase in the hydrostatic difference between the Valve Pipe Pressure and Annulus Feed Pressure.

It has been found that if the fluid in the pipe and the fluid in the annulus have the same weight per unit volume then the cracking pressure of the valve at any depth is equal to the cracking pressure of the valve at sea level. Therefore, there is no longer a concern about the valve opening because the hydrostatic pressure due the tool's depth and the weight of the fluid per unit volume in the pipe exceeded the spring cracking pressure.

The following is a list of parts and materials suitable for use in the present invention.

PARTS LIST

Part Number Description  1 inlet fluid port at box  2 outlet fluid port at pin  3 annulus pressure feed port  4 mud saver valve II (closed position)  5 mud saver valve II (open position)  6 inlet fluid conductor to the valve actuator radial port  7 valve actuator radial port  8 inlet fluid cavity between the valve actuator housing and the valve actuator sliding sleeve  9 outlet fluid flow conductor  10 mud saver valve II - final assembly  17 drill string/pipe  20 box end sub pre assembly  21 box end adaptor  22 static seal - a  23 spring closing sleeve  24 spring  25 valve actuator piston honed and polished bore  30 valve actuator pre assembly  31 valve actuator - upper cage  32 valve actuator - sliding sleeve (open/close)  33 valve actuator - sliding sleeve main seal  34 valve actuator - piston  35 valve actuator - piston seal assembly  35a valve actuator - piston seal end  35b valve actuator - piston seal female back up  35c valve actuator - piston seal ‘v’ ring - a  35d valve actuator - piston seal ‘v’ ring - b  35e valve actuator - piston seal center spacer  36 valve actuator - packing header ring  37 valve actuator - snap ring  38 valve actuator - sliding sleeve main seals spacer  39 valve actuator - optional piston w/ labyrinth groove seal  40 valve actuator housing  41 valve actuator - piston open valve pressure side  42 valve actuator - piston close valve pressure side  50 pin end sub pre assembly  51 pin end adaptor  52 fixed orifice  53 static seal b  54 cage  55 cage radial inlet ports  56 orifice inlet  57 orifice outlet orifice outlet  60 alternate mud saver valve II  70 alternate box end sub pre assembly  71 alternate annulus pressure feed port-kidney shaped  74, 84 pistons  77 alternate spring closing sleeve  80, 90 valve components  82 alternate valve actuator-sliding sleeve (open/close)  83 drill bit  91 seal 100 Box End Sub 101 Mud Saver Valve III (MSVIII) 102 Valve Actuation Housing 103 Pin End Sub 104 Plunger 105 Plunger Nose (Bolt On) 106 Plunger Mandrel 107 Bi-Directional Actuator Piston (Large) 108 Bi-Directional Actuator Piston (Small) 109 Plunger Compression Spring 110 Annulus Pressure Feed Port 111 Inlet Fluid Port at Box 112 Outlet Fluid Port at Pin 113 Plunger Seat 114 Valve Closed 115 Valve Open 116 Bi-Directional Actuator Piston 107 Large Seals to hold Annulus Pressure 117 Bi-Directional Actuator Piston 107 Large Seals to hold Internal Valve Pipe Pressure 118 Bi-Directional Actuator Piston 108 Smaller Seals to hold Annulus Pressure 119 Bi-Directional Actuator Piston 108 Smaller Seals to hold Internal Valve Pipe Pressure 150 Drill String 160 Drill Bit

All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise.

The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims. 

1. A mud saver valve, positionable at a bottom of a drill string, above a bit, which comprises: a. an elongated body portion; b. a pressure portion housing a compressible spring; c. a valve mechanism positioned within the valve; d. while in the closed position, drilling fluid cannot pass through the valve; and e. when a combination of static and pump pressure exceeds the setting pressure of the spring, the valving mechanism will be moved by concentric actuation pistons to the open position, at which point drilling fluid is allowed to flow through the valve.
 2. The valve in claim 1, wherein the valve mechanism comprises a plunger seated against a plunger seat moveable between open and closed positions within the valve by the concentric actuator pistons.
 3. The valve in claim 2, wherein the plunger is moved to the open position by means of two concentric actuator pistons.
 4. The valve in claim 1, wherein as long as the spring pressure is greater than the setting pressure, the valve remains in the closed position to allow the drill string to be disconnected, so that a section of pipe can added without the fluid draining from the drill column above the bit, resulting in a saving of fluid.
 5. The valve in claim 3, wherein by opening a closing side of the concentric actuation pistons to annulus pressure at any mud saver valve location, the valve's cracking pressure becomes independent of the depth of the tool in the hole.
 6. A mud saver valve, positionable at a bottom of a drill string, above a bit, which comprises: a. an elongated body portion; b. a pressure portion housing a compressible member, such as a coiled spring; c. a valve mechanism which comprises a plunger seated in a plunger seat in the closed position and moveable between open and closed positions within the valve; d. while in the closed position, drilling fluid cannot pass through the valve; and e. when a combination of static and pump pressure exceeds the setting pressure of the compressible member, the plunger will be moved by concentric actuator pistons to the open position, so that drilling fluid is allowed to flow through the valve.
 7. The valve in claim 6, wherein the plunger is moved to the open position by means of two concentrically disposed actuation pistons.
 8. The valve in claim 7, wherein by opening the closing side of the actuation pistons to annulus pressure at any mud saver valve location, the valve's cracking pressure becomes independent of the depth of the tool in the hole.
 9. A mud saver valve, positionable at a bottom of a drill string, above a bit, which comprises: a. an elongated body portion; b. a pressure portion housing a compressible spring; c. a valve mechanism, further comprising a plunger moveable by a pair of concentric actuator pistons between open and closed positions within the valve; d. while the plunger is seated in the plunger seat in the closed position, drilling fluid cannot pass through the valve; and e. when a combination of static and pump pressure exceeds the setting pressure of the spring, the plunger will be moved by the pair of concentric actuation pistons to the open position, and drilling fluid is allowed to flow through the valve.
 10. The valve in claim 6, wherein the plunger is unseated from the plunger seat and moved to the open position by means of a pair of concentric actuator pistons.
 11. The inventions substantially as shown and described herein. 